The investigation of airborne birch (Betula spp.) pollen grains in the area of Osijek was carried out from March to June 2016. Pollen grains were sampled with a Burkard volumetric spore trap. Birch pollination started in March while the highest concentration of pollen grains was recorded in April. Relative humidity was the most important factor for the occurrence of birch pollen grains in the atmosphere. Since the birch pollen grains has a high allergenic potential and significant variations in birch pollination duration and intensity were found, continuous monitoring of airborne birch pollen grains concentration is needed in order to inform people as well as to prevent allergic disorders associated with its allergenic effect.